Class Slides

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Class Slides

  1. 1. RFID Tags
  2. 2. What is a tag? <ul><li>Tag is a device which can be attached to an item with the purpose of identifying the item with the RFD reader </li></ul><ul><li>Contains information about the item </li></ul><ul><li>Has the capability to provide that information on request from the reader </li></ul>
  3. 3. Tag Placed on an Item
  4. 4. Some Facts About Tags <ul><li>All tags are composed of the same basic components because they offer same basic functionality, which helps to identify and track an item </li></ul><ul><li>Tags come in different forms, shapes, and sizes: these factors depend on application </li></ul><ul><li>Tags must be properly places on items so that they can be easily read by readers </li></ul>
  5. 5. Functional Components of a Tag <ul><li>Components for storing information about an item </li></ul><ul><li>Components for processing the request for information coming in from a reader </li></ul><ul><li>Components for preparing and sending the response to the reader </li></ul>
  6. 6. Chip Antenna Substrate
  7. 7. Chip <ul><li>Chip is used to generate and process a signal </li></ul><ul><li>It is an integrated circuit (IC) made of silicon </li></ul>
  8. 8. Functional Components of a Chip <ul><li>Logical unit – implements the communication protocol used for tag-reader communication </li></ul><ul><li>Memory – used to store data </li></ul><ul><li>Modulator – used for modulating the outgoing signals and demodulating incoming signals </li></ul><ul><li>Power controller – responsible for supplying power needed for operating the chip </li></ul>
  9. 9. Antenna <ul><li>A tag’s antenna receives the signal (a request for information or other command) from a reader and transmits a response signal (identification) back to the reader </li></ul><ul><li>Made of metal-based materials </li></ul><ul><li>Note the following (true for readers as well): </li></ul><ul><ul><li>Antennas are used by tags operating at UHF and microwave frequencies </li></ul></ul><ul><ul><li>Tags operating at LF and HF use inductive coils (as antennas to send and receive signal using the inductive coupling technique </li></ul></ul><ul><ul><ul><li>Why? Antenna size has to be substantial for LF </li></ul></ul></ul>
  10. 10. Substrate <ul><li>Substrate – layer that houses the chip and the antenna </li></ul><ul><li>Support structure for the tag </li></ul><ul><li>Can be made of different materials: plastic, PET, paper, glass epoxy, etc. </li></ul>
  11. 11. Substrate usage requirements <ul><li>Dissipating of static charge buildup </li></ul><ul><li>Durability under specific operating conditions </li></ul><ul><li>Mechanical protection for chip, antenna, and connections </li></ul><ul><li>Smooth printing surface </li></ul>
  12. 12. Tag Size <ul><li>Tag size may depend on the item on which the tag is placed, environment, and application </li></ul><ul><ul><li>Large tags can be used on large items, such as cars </li></ul></ul><ul><ul><li>Small, rectangular-shaped tags </li></ul></ul>
  13. 13. ISM Frequencies <ul><li>RFID systems are radio systems </li></ul><ul><li>There are other radio services in RF spectrum </li></ul><ul><li>Therefore, it is important that RFID does not disrupt other radio services </li></ul><ul><li>Industrial, scientific, and medical frequencies (ISM) can be used for RFID systems </li></ul>
  14. 14. RF Frequency Ranges >10m 3 GHz – 300 GHz Microwave Frequency <9m 300 MHz-3GHz Ultrahigh Frequency (UHF) <3m 3-20 MHz High Frequency (HF) <50cm 30-300 kHz Low Frequency (LF) Read Range for Passive Tags Frequency Range Name
  15. 15. Global UHF Frequency Bands 4 W 952-954 MHz Japan 2 W 4 W 865-868 MHz 920-925 MHz Hong Kong 2 W 865-868 MHz Europe 1 W 918-926 MHz Australia 4 W 902-928 MHz United States Power Frequency Band Area
  16. 16. Tag Types: Active and Passive <ul><li>Tag types are determined by the following factors: </li></ul><ul><ul><li>Can the tag initiate the communication? </li></ul></ul><ul><ul><li>Does the tag have its own power source? </li></ul></ul><ul><li>Active and passive tags </li></ul>
  17. 17. Passive Tags <ul><li>Passive tags do not have a power source (battery) </li></ul><ul><li>Cannot initiate communication </li></ul><ul><li>It responds to the signal sent by the reader by taking power from the reader’s signal </li></ul><ul><li>Reader’s signal “wakes up” the tag </li></ul>
  18. 18. Passive Tags <ul><li>The passive tag’s antenna (or coil) receives the signal from the reader </li></ul><ul><li>The antenna sends the signal to the IC </li></ul><ul><li>Part of the signal is used to power IC </li></ul><ul><li>The IC powers up, processes the incoming signal, and sends the response </li></ul>
  19. 19. Passive Tags <ul><li>Placement : because a passive draws energy from the reader, it must be placed within the interrogation zone </li></ul><ul><li>Size and range : since there is no battery, passive tags tend to be smaller in size and have shorter range </li></ul><ul><li>Lifespan : because there is no need to replace a battery, passive tags have a longer life </li></ul><ul><li>Memory : the memory varies from 1 bit to several kilobytes </li></ul><ul><li>Price : inexpensive (~$0.10) </li></ul>
  20. 20. 1-bit Tags (EAS) <ul><li>EAS – Electronic Article Surveillance </li></ul>
  21. 21. Passive Tags <ul><li>Passive tags can operate at any frequency: LF, HF, UHF </li></ul><ul><li>Depending on frequency, the range can be from 2 mm to 5 meters </li></ul><ul><li>The passive tags are simpler and cheaper, and therefore are more popular </li></ul><ul><li>LF passive tags are suitable for applications that require reading from a close range </li></ul>
  22. 22. Semipassive Tags <ul><li>Has its own power source (battery) but does not initiate communication </li></ul><ul><li>It responds to the signal sent by a reader by using the power from the reader’s field </li></ul><ul><li>Battery is used for powering IC </li></ul>
  23. 23. Semipassive Tags: Characteristics <ul><li>Operation : </li></ul><ul><ul><li>Can send a response only when has adequate power from the reader </li></ul></ul><ul><ul><li>Similar to passive </li></ul></ul><ul><li>Size and range : </li></ul><ul><ul><li>Larger than passive (because of battery) </li></ul></ul><ul><ul><li>Produces stronger signal </li></ul></ul><ul><ul><li>Larger read range </li></ul></ul><ul><li>Lifespan : shorter than passive </li></ul><ul><li>Memory : </li></ul><ul><ul><li>Varies </li></ul></ul><ul><ul><li>Typically has more memory </li></ul></ul><ul><ul><ul><li>Size (more room for components) </li></ul></ul></ul><ul><ul><ul><li>Battery (more energy to work with memory) </li></ul></ul></ul><ul><li>Can perform internal operations (e.g. logging temperature) even in the absence of the reader </li></ul>
  24. 24. EPC Classification of Tags <ul><li>EPC – Electronic Product Code – on organization created by MIT Auto-ID Center, which is a consortium of 120 corporations and universities </li></ul><ul><li>Each EPC tag contains EPC identification code </li></ul>
  25. 25. Class 3 capabilities plus extras Can initiate communication; power their own communication; tag-to-tag communication possible Read and rewrite A 4 Class 4 capabilities plus extras Can initiate communication; power their own communication; tag-to-tag communication possible Read and rewrite A 5 Class 2 capabilities plus extras, such as integrated sensors Does not initiate communication Read and rewrite SP 3 Encryption Does not initiate communication Read and write-once P 2 The EPC number is not encoded during manufacturing but can be encoded later Does not initiate communication Read and write-once P 1 Does not initiate communication Same as Class 0, but you can write once P 0+ EPC number is encoded during manufacture and can be read by a reader Does not initiate communication Read-only P 0 Other Properties Communication Memory Type Class
  26. 26. Labeling a Tag <ul><li>Inlay – bare-bones tag (antenna, chip, substrate) </li></ul><ul><li>Insert – an inlay inserted between a label in the front and an adhesive layer in the back </li></ul><ul><ul><li>Thick inserts for harsh environments </li></ul></ul><ul><ul><li>Paper-thin inserts for parcels </li></ul></ul><ul><ul><li>Postage stamp-sized inserts (DVDs) </li></ul></ul>
  27. 27. Smart Labels <ul><li>Smart Label – a barcode label that has an embedded RFID tag inside </li></ul><ul><li>You can print readable/scannable information on the label </li></ul><ul><li>Components </li></ul><ul><ul><li>Inlay </li></ul></ul><ul><ul><li>Label face stock – covers the top of inlay and provides area for printing information </li></ul></ul><ul><ul><li>Adhesive </li></ul></ul><ul><ul><li>Release liner – at the bottom of inlay </li></ul></ul>
  28. 28. Tag Housing
  29. 29. Placing Tags <ul><li>Materials </li></ul><ul><li>Antenna polarization </li></ul><ul><ul><li>Linear </li></ul></ul><ul><ul><ul><li>Horizontal – align </li></ul></ul></ul><ul><ul><ul><li>Vertical - align </li></ul></ul></ul><ul><ul><ul><li>Circular - OK </li></ul></ul></ul><ul><li>Experimenting </li></ul>
  30. 31. Conclusion <ul><li>The basic functionality of any tag is to store information about the item to which it is attached and to provide this information when requested by a reader </li></ul><ul><li>Tags have three basic components: chip, antenna, substrate </li></ul><ul><li>Two types of tags: active (can initiate communication) and passive (cannot initiate communication) </li></ul><ul><li>Tag should be placed in a way that makes it readable to the reader </li></ul>

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